Apolipoprotein B (APOB) is a critical structural and functional protein in lipid metabolism that exists in two forms: apoB-48 in chylomicrons and apoB-100 in VLDL and LDL particles 1. ApoB-100 serves as the essential ligand for LDL-receptor-mediated endocytosis, enabling cellular uptake of LDL particles 1. The protein plays a central role in triglyceride-rich lipoprotein (TRL) biosynthesis and metabolism, directly impacting cardiovascular health 2. APOB mutations cause two monogenic dyslipidemias: familial ligand-defective apoB-100 (missense mutations in the LDL-receptor-binding domain causing hypercholesterolemia and premature coronary artery disease) and familial hypobetalipoproteinemia (other mutations causing hypocholesterolemia and atherosclerosis resistance) 1. APOB variants account for approximately 14 of 224 familial hypercholesterolemia-associated mutations identified in some populations 3. Clinically, apoB measurement outperforms LDL-cholesterol in predicting atherosclerotic cardiovascular disease risk 4. Achieving apoB levels <65 mg/dL associates with enhanced plaque stabilization, increased fibrous cap thickness, and reduced thin-cap fibroatheroma prevalence after acute coronary syndromes 5. Specific APOB polymorphisms (rs1801701, rs1042031) correlate with increased ischemic stroke risk 6. These findings support apoB as a superior therapeutic target for lipid-lowering interventions.